In order to measure the flow rate and hence the volume of flow of molten metals, a magnetic flowmeter can be used. Magnetic flowmeters are used due to the extreme temperature of the molten metals that usually run in the 200.degree. F.-3000.degree. F. range.
Magnetic flowmeters known in the prior art such as King, U.S. Pat. No. 3,3566,684 incorporates the use of closed flowtubes through which the molten metal flows when measuring the volumetric flow rate of the metals. The closed flowtube prevents the operator and atmosphere from directly contacting the molten metal so as to prevent injury and atmospheric contamination of the metal. There is an inherent drawback in the use of a closed flowtube. After periodic use, sludge from the liquid metal accumulates inside of the flowtube around the area of the sensing electrodes of the flowmeter. This build-up of sludge decreases the readings of the flowmeter, thereby rendering the meter inaccurate. When this build-up occurs, the flowtube must be replaced resulting in losses due to downtime. The flowtube itself can also be quite expensive especially when the tube must be replaced several times a year. It would be desirable to incorporate a flowtube within a magnetic flowmeter that could be cleaned periodically without having to remove and replace the entire flowtube. This invention provides just such a device.